When target signals are received by a radar, they are occasionally received with embedded multipath errors. Multipath errors arise when a signal reaches the receiver from two or more paths. This often occurs if the signal reflects off a large surface, such as a building, a land mass, water, or the atmosphere, resulting in two signals from the same transmission (often the line-of-sight signal and the reflected signal) reaching the receiver at nearly the same time.
Embedded multipath interference will distort the signal in an unknown, but not random, way. If several detections are made on, for example, a ballistic target, the detections will not follow the smooth parabolic arc of the ballistic target, but instead show a higher order curve that deviates about the parabolic curve. The position errors in these detections could cause the radar to classify the target incorrectly, to break track, or to estimate its position or path incorrectly. Thus, mitigating multipath errors is essential for the accurate and reliable tracking of targets in a multipath environment.
Most efforts to mitigate multipath interference involve transmitting wideband (or sweeping narrowband) signals, installing multipath fences or covering the area with absorber material, detecting with multiple, spatially diverse antennas, or using algorithms specifically designed for a particular emplacement scenario. These efforts, however, are limited to a specific context and are not adaptable to any emplacement scenario.
Accordingly, a need exists in the art for a method and system to mitigate the effect of multipath errors in nearly any emplacement scenario.